Maybe I'm just too impressed with this Touchpress company, but I think this one is quite a simple, sophisticated app. Steve Reich's Clapping Music is a music game that tests (or improves) your sense of rhythm. Fun!
This amazing app by Touchpress lets users experience the masterpiece to the fullest with a synchronized score, visualized orchestration, expert commentary, etc. Other similar apps by the same company include Liszt Sonata, and Vivaldi's Four Seasons. Totally impressed!